are cosmetical only, totally harmless and can be ignored, was covered
already some time ago, see ml archive.

2. Setting up linux-image-2.6.26-2-alpha-generic (2.6.26-21lenny3) ...
Hmm. The package shipped with a symbolic link
/lib/modules/2.6.26-2-alpha-generic/source
However, I can not read the target: No such file or directory
Therefore, I am deleting /lib/modules/2.6.26-2-alpha-generic/source